Interesting situation with a data center client in Chicago. They were happily on ComEd Rate BGSGS (Secondary General Service) with 80-100kW demand for two years. Added server capacity last month and hit 850kW peak. ComEd automatically moved them to Rate BGS (Primary General Service) but the demand charges are brutal - $16.83/kW vs previous $9.22/kW. Client is freaking out over $14K monthly bills. Any options for managing this transition? - Susan P.
ComEd demand threshold crossing - client jumped from 100kW to 850kW
Susan, once you cross ComEd's 400kW threshold you're automatically moved to primary voltage rates. The demand charge increase is painful but check if they qualify for Rate BGS-TOU (time of use). If they can shift some server loads to off-peak hours, the demand charge drops to $12.15/kW during off-peak periods. Also verify they're actually taking primary voltage service - if still on secondary they should be on Rate BGSGS-HT. - Randy D.
Randy's right about the voltage level. I had a similar ComEd account that was billed on primary rates but actually served at secondary voltage. ComEd corrected it and refunded 8 months of overcharges. Always verify the actual service voltage matches the rate schedule voltage requirements. - Sarah M.
Checked the service details - they're definitely on secondary voltage but demand over 400kW. ComEd rep says they automatically go to Rate BGSGS-HT (High Tension Secondary) at $14.52/kW demand charge. Still expensive but better than the $16.83 they're charging now. Filing a rate correction request. - Susan P.
Susan, also look at power factor penalties. Data centers often have poor power factor from all the switching power supplies. ComEd penalizes anything below 85% PF. Adding power factor correction capacitors might save more than you think. - Ed T.
Ed, good call on power factor. Last bill showed 78% PF with $2,100 penalty. Client is getting quotes for automatic PF correction equipment. Between the rate correction and PF improvement looking at $4K monthly savings. Thanks everyone. - Susan P.
This thread is gold for understanding ComEd's demand thresholds. I'm dealing with a manufacturing client who might cross 400kW next year. Better to plan for the rate change instead of getting surprised like Susan's client did. - Craig P.